EP0738542B1

EP0738542B1 - Trigger type liquid discharge device

Info

Publication number: EP0738542B1
Application number: EP95935573A
Authority: EP
Inventors: Tadao Yoshino Kogyosho Co. Ltd. SAITO; Shigeru Yoshino Kogyosho Co. Ltd. HAYAKAWA
Original assignee: Yoshino Kogyosho Co Ltd
Current assignee: Yoshino Kogyosho Co Ltd
Priority date: 1994-10-26
Filing date: 1995-10-26
Publication date: 2008-05-07
Anticipated expiration: 2015-10-26
Also published as: EP1923143A3; DE69535779D1; EP1923143A2; AU3754095A; AU708396B2; CN1071599C; EP1923143B1; DE69535748D1; EP1310305A3; EP0738542A4; JP3720054B2; CN1137764A; WO1996013334A1; EP1310305A2; CA2179888C; KR100407125B1; CA2179888A1; EP1310305B1; EP0738542A1

Abstract

A valve structure adapted to open only at a normal discharge pressure of a liquid is arranged upstream of a discharge port of a nozzle head on a trigger type liquid discharge device, and a flow passage, through which a residual pressure in a liquid flow passage at the completion of discharge is returned to a liquid vessel, is provided in a cylinder on a pump mechanism to thereby prevent insufficiency in a discharge pressure of a liquid being discharged or liquid dripping from the discharge port at start-up of discharge or at the completion of discharge due to the residual pressure in the liquid flow passage.

Description

Field of the Invention

This invention relates to an improved trigger type liquid discharge device to be fitted to an opening of a liquid container containing liquid in order to discharge the liquid.

Prior Art

Figure 22 of the accompanying drawings illustrates a known trigger type liquid discharge device disclosed in U.S. Patent No. 4,819,835 and so designed as to be fitted to the opening of a liquid container containing liquid in order to discharge the liquid.
In the known trigger type liquid discharge device as disclosed in U.S. Patent No. 4,819,835 , a pump unit E is arranged in parallel with a horizontally disposed discharge pipe unit F as illustrated in Figure 22.
The trigger type liquid discharge device as illustrated in Figure 22 is provided with a fitting section 101 by which the liquid discharge device is secured to an opening of a liquid container. When a trigger 102 of the device is pushed in a direction indicated by arrow J', a pushing member 103 by turn depresses a transversal groove 105 of a head 104 of piston unit G of the device so as to move a piston I until an end face 106 of the piston I abuts a bottom wall 107 of a cylinder H. Thus, the liquid filled in a cylinder chamber 108 is pushed out of the device through a liquid suction/discharge port 109 to a liquid flow path 110 so as to push a discharge valve body 111 under its pressure.
The discharge valve body 111 has a resiliently deformable section 112, which is resiliently deformed under the pressure of the liquid to open discharge valve seat 113. Thus, liquid is allowed to flow into a flow path 115 of the discharge pipe F through discharge valve chamber 114. Then the liquid flows into another flow path 116 and then a shallow groove M arranged between a liquid guide L and a short pipe K of a nozzle head J. Then, the liquid flows into still another flow path 117 in which spins the liquid, and is finally discharged through a discharge aperture 118.
Meanwhile, the piston I compresses a spring 119 contained in the piston unit. A ball valve 120 also contained in' the unit is forced to abut a suction valve seat 121 under the pressure applied by the liquid of the flow path 110.
After completing to discharge the liquid through the discharge aperture 118, and if the trigger 102 is released, the piston is returned to a position shown in Figure 22 by the resilient force of the spring 119 to expand the cylinder chamber 108 so as to generate a negative pressure in the chamber 108. Such negative pressure acts on the discharge valve body 111 and the ball valve 120 to cause the discharge valve body 111 to firmly abut and close the discharge valve seat 113. Consequently, the ball valve 120 is moved away from the suction valve seat 121 to allow liquid in the liquid container to flow through a suction pipe 122, the liquid flow path 110 and the port 109 into the cylinder chamber 108 so that the device is made ready for another discharge operation.
The cylinder H is provided in a part of its peripheral wall with an air intake port 123. The air intake port 123 is held in communication with the liquid container, on which the device is mounted by means of the fitting section 101 of the device, through air ducts 124 and 125.
The piston I has a stroke end side resilient annular skirt 126 extending toward the bottom wall 107 of the cylinder H and an approach end slide resilient annular skirt 127 extending toward the opening of the cylinder H. Said annular skirts 126 and 127 are held in close contact with the inner wall of the cylinder.
When the piston I is located in a stroke end position where the end surface 106 abuts the bottom wall 107 of the cylinder H, an edge 128 of the approach end side annular skirt 127 is positioned beyond the air intake port 123 of the cylinder H toward the bottom wall 107. Under this condition, air is introduced into the liquid container as the air intake port 123 communicates with an opening 129 of the cylinder H that is exposed to the atmosphere. If, to the contrary, the piston I is located at an approach end position as indicated in Figure 22, the air intake port 123 is closed as it is positioned between the two annular skirts 126 and 127 so that no liquid would flow out through the air intake port 123 if the liquid container is tumbled down by mistake.
The trigger type liquid discharge device as disclosed in U.S. Patent No. 4,819,835 and summarily described above functions correctly so long as a user uses it properly and operates the trigger in such a way that the piston completely moves from the stroke end position to the approach end position.
In Figure 22, reference symbol N denotes a cap for covering the discharge aperture 117 and reference symbol O denotes a pivot of the cap N.
While the trigger type liquid discharge device as disclosed in U.S. Patent No. 4,819,835 operates satisfactorily efficiently for discharging liquid, it is accompanied by certain drawbacks particularly in terms of the pressure of the liquid flowing from the cylinder chamber 108 to the discharge aperture 118 during liquid discharging operation. More specifically, referring to Figure 23, during time TS from when the piston I starts moving from the approach end toward the stroke end, the liquid pressure PS in the shallow groove M and the flow path 117 which constitutes a spinning groove does not rise high enough to give rise to a jet stream of liquid. During time TE from the end of a liquid discharge phase when the piston I reaches to the stroke end and stops discharging liquid, residual pressure PE is found over a large area including the cylinder chamber 108, the port 109, the liquid path 110 and the discharge chamber 114.
As a result, liquid may drip out from the discharge aperture 118 at the beginning and the end of a discharge phase. When liquid is discharged as foam, large bubbles of liquid that have not sufficiently foamed may come out through the aperture. The trigger type liquid discharge device of the prior art has such drawbacks.
EP-A-0701950 discloses a flowing-out passage consisting of a small-diameter portion located at the cylinder side and a large-diameter portion located at the orifice side. Provided in the passage is a secondary valve. Skirt-shaped seals are mounted on a secondary valve and set in sliding contact with the inner surface of the flowing-out passage to prevent communication between the small-diameter and large-diameter portions. The secondary valve has a valve spring, a valve body, and a valve seat located at the orifice side. The valve spring sets the valve body in contact with the valve seat. Liquid pressures are applied on the secondary valve on both sides. The valve body can be moved away from the valve seat against the force of the valve spring, by a difference between the liquid pressures.

SUMMARY OF THE INVENTION

It is an aim of the present invention to provide a trigger type liquid discharge device having a configuration substantially as shown in Figure 22 and improved such that no liquid drips out through the discharge aperture of the device even in the initial and final stages of the operation of activating the trigger and still the device satisfactorily operates for discharging liquid.
According to a first aspect of the present invention, the above aim is addressed by providing a trigger type liquid discharge device comprising a container, a pump unit having a cylinder and a piston, a discharge pipe having a discharge aperture, and a trigger for reciprocating the piston, wherein liquid drawn up from the container is discharged through the discharge aperture by movement of the piston to a stroke end, in which:

a liquid guide is arranged in a liquid flow path disposed upstream relative to the discharge aperture, said liquid guide comprising a valve body for closing the liquid flow' path, a pressure bearing sleeve formed integrally with the valve body, an anchor member to be secured to the discharge pipe, and a spring member for coupling said integrally formed valve body and the pressure bearing sleeve with the anchoring member,
said pressure bearing sleeve has a pressure bearing surface facing the upstream side of the liquid flow path for bearing the liquid pressure,
an area of said pressure bearing surface is so selected that a force generated by a proper liquid discharge pressure that is applied to said pressure bearing surface is greater than the sum of a resilient force of the spring member and a force applied to the valve body and directed to the downstream side of the liquid flow path.

According to a second aspect of the present invention, the foregoing aim is addressed by providing a trigger type liquid discharge device comprising a container, a pump unit having a cylinder and a piston, a discharge pipe having a discharge aperture, and a trigger for reciprocating the piston, wherein liquid drawn up from the container is discharged through the discharge aperture by movement of the piston to a stroke end, in which:

a liquid guide is arranged in a liquid flow path disposed upstream relative to the discharge aperture, said liquid guide comprising a valve body for closing the liquid flow path, a pressure bearing sleeve formed integrally with the valve body, an anchor member to be secured to the discharge pipe, and a spring member for coupling said integrally formed valve body and the pressure bearing sleeve with the anchoring member,
said pressure bearing sleeve has a pressure bearing surface facing the upstream side of the liquid flow path for bearing the liquid pressure,
an area of said pressure bearing surface is so selected that a force generated by a proper liquid discharge pressure that is applied to said pressure bearing surface is greater than the sum of a resilient force of the spring member and a force applied to the valve body and directed to the downstream side of the liquid flow path,
an inner peripheral wall of the cylinder is provided with a plurality of short and shallow grooves at a portion adjacent to a bottom wall of the cylinder, said short and shallow grooves running longitudinally,
the inner peripheral wall of the cylinder is provided with an air intake port communicating with an inside of the container,
the piston is formed with a pair of annular skirts held in close contact with the inner peripheral wall of the cylinder, and
a gap separating said pair of annular skirts is so selected that, when one of the annular skirts rides on the short and shallow grooves of the cylinder, the other of the annular skirts is brought into close contact with the inner peripheral wall of the cylinder at a position close to an open edge of the cylinder than the air intake port.

Preferably, a groove for the intake of air is formed on the inner surface of the cylinder between a first position where the annular skirt rides on the short and shallow groove and a second further position which is near the air intake port relative to a third position where the annular skirt is positioned when the piston is positioned at the approach end.
Such a device is prevented from excessively decreasing the pressure in the container due to the reciprocation of the pump mechanism. '

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an enlarged longitudinal sectional view of a first embodiment of a liquid discharge device in accordance with claim 1, showing the inside of the device before it starts discharging liquid.
Figure 2 is an enlarged longitudinal sectional view of the nozzle head of the embodiment of Figure 1.
Figure 3 is an enlarged front view of the nozzle head of Figure 2.
Figure 4 is an enlarged lateral view of an integral structure comprising a valve body, a pressure bearing sleeve, an anchoring member and a spring member as shown in Figure 1.
Figure 5 is a front view of the integral structure of Figure 4.
Figure 6 is a rear view of the integral structure of Figure 4.
Figure 7 is an enlarged partially sectional lateral view of the integral structure of Figure 4, obtained by rotating it by 90° from the position of Figure 4.
Figure 8 is an enlarged longitudinal sectional view of the embodiment of Figure 1, showing the inside when it is discharging liquid.
Figure 9 is an enlarged longitudinal sectional view of a second embodiment of a liquid discharge device in accordance with claim 1, showing the inside of the device before it starts discharging liquid.
Figure 10 is an enlarged lateral view of an outer member of the liquid guide of the embodiment of Figure 9.
Figure 11 is a rear view of the member of Figure 10.
Figure 12 is a lateral partially sectional view of the member of Figure 10, obtained by rotating it by 90° from the position of Figure 10.
Figure 13 is an enlarged lateral partially sectional view of an inner member of the liquid guide of the embodiment of Figure 9.
Figure 14 is a front view of the member of Figure 13.
Figure 15 is an enlarged longitudinal sectional view of the embodiment of Figure 9, showing the inside when it is discharging liquid.
Figure 16 is an enlarged longitudinal sectional view of the pump unit of a first embodiment of liquid discharge device in accordance with claim 3, showing the inside when it is in a standstill state.
Figure 17 is an enlarged longitudinal sectional view of the pump unit of Figure 16, showing the inside during an air intake phase.
Figure 18 is an enlarged longitudinal sectional view of the pump unit of Figure 17, showing the inside during a liquid discharge phase, showing the state after that of Figure 17.
Figure 19 is an enlarged longitudinal sectional view of the pump unit of Figure 17, showing the inside when the discharging operation is finished and it is moved into a residual pressure relieving phase.
Figure 20 is an enlarged longitudinal sectional view of another embodiment in accordance with the invention of claim 3.
Figure 21 is an enlarged longitudinal sectional view of an embodiment of the liquid discharge device in accordance with the invention of claim 2, showing a principal part thereof.
Figure 22 is an enlarged longitudinal sectional view of a conventional trigger type liquid discharge device.
Figure 23 is a graph showing the relationship between the elapsed time and the discharge pressure in an entire phase of operation of a trigger type liquid discharge device.

THE PREFERRED EMBODIMENTS

For the purpose of the present invention, all the components of a trigger type liquid discharge device in accordance with the invention operate similarly as their counterparts of a conventional trigger type liquid discharge device illustrated in Figure 22 and described above except the nozzle head section and the pump unit. Thus, those components that are similar to or the same as their counterparts of Figure 22 should be referred. Throughout Figures 1 to 21, same and identical components are denoted by same reference symbols.
Figures 1 through 8 illustrate in enlarged views a nozzle head section 1 of a first embodiment of liquid discharge device in accordance with claim 1. The nozzle head section 1 comprises a nozzle head 2, a liquid guide 3, a spin element 4 and a nozzle tip 6 having a discharge aperture 5.
The nozzle head 2 is provided with a valve seat 8 arranged in a liquid flow path 7 at a position upstream relative to the discharge aperture 5. Said liquid flow path 7 communicates with the liquid flow path 115 of the discharge pipe unit F via a liquid flow path 9.
As shown in Figs. 4 through 7, said liquid guide 3 comprises a valve body 10 which abuts on the valve seat 8 to close the liquid flow path 7, a pressure bearing sleeve 11 integrally formed with the valve body 10, an anchoring member 12 to be secured to the spin element 4 and a spring member 13 for coupling the discharge valve 10 and the pressure bearing sleeve 11 to the anchoring member 12.
As shown in Figs. 5 and 7, the pressure bearing sleeve 11 has a pressure bearing surface 14 arranged to face the upstream side of the liquid flow path 7 for bearing liquid pressure.
As seen from Figs. 5 through 8, the valve body 10 and the pressure bearing sleeve 11 is coupled by means of a sleeve 15 provided with a window 16 which communicates to the liquid flow path 9. As shown in Fig. 1, the pressure of the liquid is applied to the liquid bearing surface 14 when the valve body 10 abuts the valve seat 8 to block the liquid flow paths 7 and 9.
Said sleeve 15 is integrally formed with a guide sleeve 17 extending to the side of the liquid flow path 9. Said guide sleeve 17 is slidably inserted into the inside of a guide sleeve 18 of the spin element 4 projecting toward the liquid flow path 7, such that it may slidably move without encountering any significant resistance and hence the valve body 10 may move back and forth relative to the valve seat 8, keeping its proper posture. The anchoring member 12 and the spring member 13 are arranged in an annular space 4C between the guide sleeve 18 and an outer sleeve 4B of the spin element 4.
As seen from Figs. 1, 2, 3 and 8, the nozzle head 2 has a recess 19 at the front end thereof for bearing and securing or holding the nozzle tip 6 in such a way that a flow path 20 is produced in the form of a spin groove.
Reference numeral 21 in the drawings denotes a bore for bearing the pivot 0 of the cap N shown in Figure 22.
The nozzle head 2 is provided with an annular groove 2A for bearing a corresponding annular section 4A of the front end of the spin element 4, and an another annular groove 2B for tightly but slidably bearing the pressure bearing sleeve 11.
The nozzle head 2 is so designed that, after fitting the liquid guide 3 thereinto, an outer sleeve 2C is secured to the spin element 4 by means of undercuts 2D. Thus, these are easily assembled.
Referring to Fig. 1. the valve body 10 is pressed against the valve seat 8 in Fig. 1 under liquid pressure applied thereto within the horizontal projection surface area X and by the resilient force of the spring member 13.
On the other hand, the pressure bearing sleeve 11 is pressed toward the upstream of the liquid flow paths under liquid pressure applied to the horizontal projection surface area of the pressure bearing surface 14.
Therefore, by selecting an appropriate value for the horizontal projection surface area of the pressure bearing surface 14 such that the force generated by the proper liquid discharge pressure that is applied to said horizontal projection surface area of the pressure bearing surface 14 is greater than the sum of the force generated by the proper liquid discharge pressure that is applied to the horizontal surface area of the valve body 10 and the resilient force of the spring member 13, the valve body 10 is moved and opened under liquid pressure the instance when the liquid pressure reaches the level of the proper liquid discharge pressure.
Thus, in accordance with claim 1, the valve body 10 is opened when the liquid pressure reaches the proper liquid discharge pressure Y as shown in Figure 23 so that liquid is discharged in the direction indicated by arrow Z in Figure 8. The valve body is closed when the liquid pressure falls under the proper liquid discharge pressure. With such an arrangement, liquid can be effectively prevented from dripping out of the discharge aperture 5 in the initial and final stages of discharging liquid due to insufficient liquid pressure.
Figures 9 through 15 show, in an enlarged scale, the nozzle head 201 of a second embodiment of liquid discharge device in accordance with claim 1. While the nozzle head of the above described first embodiment comprises a one-piece liquid guide 3, the liquid guide 203 of the second embodiment comprises two pieces of an outer member 222 including a valve body 210 and an inner member 223.
Note that the nozzle head 202 including the nozzle tip 206 of this embodiment is otherwise structurally the same as its counterpart of the first embodiment.
As shown in Figures 10, 11 and 12, the outer member 222 of the liquid guide 203 comprises a valve body 210, a pressure bearing sleeve 211, an anchoring member 212 to be secured to the spin element 204, a spring member 213 and a guide sleeve 217.
The valve body 210 blocks the liquid flow path 207 arranged on the side of the nozzle tip 206 and the upstream side liquid flow path 209.
The spring member 213 couples the anchoring member 212 to the valve body 210, the pressure bearing sleeve 211 and the guide sleeve 217.
The inner member 223 shown in Figs. 13 and 14 is put into and rigidly secured to the guide sleeve 217. Said inner member 223 comprises a head section 224, a flange 225 and a slide sleeve 226.
The head section 224 is press-fit into a sleeve section 215 which is formed by extending from the valve body 210 of the outer member 222 toward the upstream side of the liquid flow paths.
The flange 225 is press-fit into the guide sleeve 217.
The slide sleeve 226 is slidably inserted into the inside of guide sleeve 218 of the spin element 204 such that it may freely slide without encountering any significant resistance.
The head section 224 has a through bore 227 arranged at the center thereof and a radial groove 229 arranged at a top 228 thereof.
The sleeve section 215 of the outer member 222 has a radial window hole 230 corresponding to the radial groove 229 arranged in the head section 224 of the inner member 223.
On the other hand, a guide sleeve 231 extending from the valve seat 208 of the nozzle head 202 toward the upstream side of the liquid flow paths also has a radial window hole 232 corresponding to the radial window hole 230.
With the above described arrangement, the liquid flow path 233 of the discharge pipe F is held in communication with the annular groove 222B arranged in front of the pressure bearing surface 214 of the pressure bearing sleeve 211 of the outer member 222 via the port 234 of the spin element 204, the liquid flow path 209, the inner space 226A of the slide sleeve 226 of the inner member 223, the through bore 227, the groove 229 and the window holes 230 and 232.
In the above described second embodiment, the valve body 210 is pressed against the valve seat 208 by liquid pressure applied to the horizontal projection surface area of the inner member 223 facing the liquid flow path 209 and by the resilient force of the spring member 213. The outer member 222 is pressed toward the upstream side of the liquid flow paths under liquid pressure in the liquid flow path 209, which pressure is applied to the horizontal projection surface area of the pressure bearing surface 214 of the pressure bearing sleeve 211 of the outer member 222.
An appropriate value for the horizontal projection surface area of the pressure bearing surface 214 is selected such that the component of the force generated by the proper liquid discharge pressure applied to said horizontal projection surface area of the pressure bearing surface 214 is greater than the sum of the force generated by the proper liquid discharge pressure applied to the horizontal surface area of the inner member 223 facing the liquid flow path 209 and the resilient force of the spring member 213. When the liquid pressure reaches the level of the proper liquid discharge pressure, the valve body 210 is moved from the valve seat 208 and opened under liquid pressure to make the liquid flow path 209 communicate with the liquid flow path 207 arranged downstream relative to the valve seat 208 as shown in Fig. 15 so that liquid is discharged through the discharge aperture 205 of the nozzle tip 206.
When the liquid pressure falls under the proper liquid discharge pressure, the valve body 210 is closed to completely stop any discharge of liquid so that liquid can be effectively prevented from dripping out as in the case of the first embodiment.
In the second embodiment as described above, the inner member 223 is press-fit into the outer member 222 that is provided with a liquid guide 203 having a valve body 210, and the opening of the slide sleeve 226 of the inner member 223 faces vis-a-vis the liquid flow path 209. Thus, the horizontal projection surface area of the slide sleeve 226 as indicated by arrow S in Figs. 9 and 15 can be made very small relative to the corresponding surface area of the first embodiment, so as to increase the ratio of said horizontal projection surface area of the slide sleeve 226 to the horizontal projection surface area of the pressure bearing surface 214 of the pressure bearing sleeve 211.
This means that the initial priming operation for eliminating air in the liquid cylinder and drawing up liquid through the cylinder by reciprocating the piston can be carried out in a short period of time.
Additionally, since the valve body 210 of the second embodiment can be opened simply by using pneumatic pressure in the initial priming operation, the discharge valve 111 as shown in Fig. 33 can be omitted.
Figs. 16 through 19 show, in enlarged longitudinal cross section, the pump unit of a first embodiment of liquid discharge device in accordance with claim 3. The - pump unit 22 comprises a cylinder 23 and a piston 24.
The cylinder 23 comprises an outer sleeve 25 designed to cooperate with a piston 24, and an inner sleeve 27 in which a spring 26 is arranged to urge the piston 24 to move back to the retracted position.
A cylinder chamber 28 is formed between the outer sleeve 25 and the inner sleeve 27 and held in communication with a liquid flow path 110 provided with a ball valve 120 (which operates as a check valve) by way of a liquid intake/discharge port 30 bored through a bottom wall 29 the cylinder chamber 28.
An inner peripheral wall 31 of the outer sleeve 25 is provided with a plurality of short and shallow grooves 32 running longitudinally near the bottom wall 29.
While the illustrated short and shallow grooves 32 are arranged on the inner peripheral wall 31, pairs of short and low ridges may alternatively be formed longitudinally such that the interval separating each pair of ridges functions as a short groove and shallow groove.
The outer sleeve 25 is additionally provided at a position near the bottom wall 29 with an air intake port 123 for drawing out air into the container to which the trigger type liquid discharge device is fitted. Also, at a position closer to the opening 129 of the outer sleeve 25 than the air intake port 123, the outer sleeve 25 is provided with a plurality of shallow outer air feeding grooves 33 running longitudinally.
Note that, in the illustrated embodiment, the shallow grooves 32 are short in the longitudinal direction but rather wide in the peripheral direction.
A stroke end side end portion of the piston 24 located close to the bottom wall 29 of the cylinder 23 has a rather thick wall portion, which is provided at the inner and outer peripheries with respective resilient annular skirts 35 and 36 extending toward the stroke end side to closely contact with the inner peripheral wall 31 of the outer sleeve 25 and the outer peripheral wall 34 of the inner sleeve 27 respectively.
The thick wall portion is additionally provided on the approach end side peripheral edge thereof with an annular skirt 37 extending toward the approach end side to closely contact with the inner peripheral wall 31 of the outer sleeve 25.
The interval separating the resilient annular skirts 35 and 37 is so selected that, as seen from Fig. 19, when the annular skirt 35 rides on the short and shallow grooves 32, the annular skirt 37 closely contact with the inner peripheral wall 31 of the outer sleeve 25 at an edge portion 38 of the air intake port 123 located close to the opening 129 of the outer sleeve 25.
An interval between the shallow outer air feeding grooves 33 and the air intake port 123 is so selected that, as seen from Fig. 16, when the piston 24. takes the approach end position, the shallow outer air feeding.grooves 33 and the air intake port 123 are closed by the annular skirts 35 and 37, whereas, when the piston 24 is in the compression stroke, the annular skirt 37 rides on the shallow outer air feeding grooves 33 as shown in Fig. 17 and outer air is fed into the container via the air intake port 123 as shown by arrow P in Fig. 17, while the communication between the shallow outer air feeding grooves 33 and the air intake port 123 is blocked by the annular skirt 37 before the end of the compression stroke.
When the annular skirt 35 rides on the short and shallow groove 32 at the end of the compression stroke, the annular skirt 35 closely contacts with the portions 31A of the inner peripheral wall 31 adjacent to the respective short and shallow grooves 32 but does not falls into the grooves 32. Thus, the liquid remaining in the remaining portion 28a of the cylinder chamber 28 and remaining in the liquid flow paths between the port 30 and the discharge aperture 118 (illustrated in Figure 22) returns into the container under its own pressure by way of the short and shallow grooves 32, the gap 31B between the annular skirt 35 and the annular skirt 37 and the air intake port 123, so that any residual pressure would not affect the discharge aperture 118 and no liquid would drip out therethrough after the end of a discharging cycle.
The low projecting ridges 84 may be replaced by shallow outer air feeding grooves 33 illustrated in Figure 16 or by a boundary 503 illustrated in Figure 20.
In accordance with claim 2, since the residual pressure is removed by positively causing the front end 331 of the pin body 330 to deform the resilient valve 323, any possible leakage of pressure and insufficient removal of residual pressure due to an accumulated effect of dimensional errors of the related components can be completely avoided to make the operation of dimensional control during the process of manufacturing the components very easy.
Figure 20 illustrates an embodiment of claim 3. In the first embodiment illustrated in Figure 16, a plurality of shallow outer air feeding grooves 33 are depressedly and longitudinally formed on the inner surface of the outer sleeve 25 of the cylinder 23. On the other hand, in this embodiment illustrated in Figure 20, the outer cylinder 25 has the inner surface which comprises an inner surface 502 at the opening 129 side and an inner surface 501 provided at an area where the resilient annular skirts 35, 36, 37 moves upon a liquid discharge phase. The inner surface 502 has a diameter slightly larger than a diameter of the inner surface 501. A boundary 503 of the diameter between the inner surface 502 and the inner surface 501 has a wave shape as illustrated by a dotted line in Figure 31. When the annular skirt 37 reaches to the wave-shaped boundary 503, outer air is introduced through the opening 129 to the air intake port 123.
This embodiment has the same construction as that of the embodiment illustrated in Figure 16 except the constructions of the above described wave-shaped boundary 503 and a liquid flow sleeve 505 having a check valve 504.
According to this embodiment of claim 3, it is easy to remove the cylinder 23 from a metal mold.
Figure 21 shows, in enlarged cross section, a principal area of a trigger type liquid discharge device in accordance with claim 3. As shown, the trigger type liquid discharge device has a single nozzle head section 70 comprising a nozzle head 2, a liquid guide 3, a spin element 4 and a nozzle tip 6 the same as those of a liquid discharge device in accordance with claim 1 and illustrated in Figures 1 though 8, while it also has a pump unit 71 comprising cylinder members 39, 40, 41 and 42 and piston members 43, 44, 46, 48, 49 and 50. With this arrangement, again, undesired liquid and bubbles can be effectively prevented from dripping out of the discharge aperture 5.

Claims

A trigger type liquid discharge device comprising a container, a pump unit having a cylinder and a piston, a discharge pipe (F) having a discharge aperture (5), and a trigger (102) for reciprocating the piston, wherein liquid drawn up from the container is discharged through the discharge aperture by movement of the piston to an stroke end, characterized in that
a liquid guide (3) is arranged in a liquid flow path (7) disposed upstream relative to the discharge aperture (5), said liquid guide (3) comprising a valve body (10) for closing the liquid flow path (7), a pressure bearing sleeve (11) formed integrally with the valve body (10), an anchor member (12) to be secured to the discharge pipe, and a spring member (13) for coupling said integrally formed valve body (10) and the pressure bearing sleeve (11) with the anchoring member (12),
said pressure bearing sleeve (11) has a pressure bearing surface (14) facing the upstream side of the liquid flow path (7) for bearing the liquid pressure,
an area of said pressure bearing surface (14) is so selected that a force generated by a proper liquid discharge pressure that is applied to said pressure bearing surface (14) is greater than the sum of a resilient force of the spring member (13) and a force applied to the valve body (10) and directed to the downstream side of the liquid flow path (7).
A trigger type liquid discharge device comprising a container, a pump unit having a cylinder and a piston, a discharge pipe (F) having a discharge aperture (5), and a trigger (102) for reciprocating the piston, wherein liquid drawn up from the container is discharged through the discharge aperture by movement of the piston to an stroke end, characterized in that
a liquid guide (3) is arranged in a liquid flow path (7) disposed upstream relative to the discharge aperture (5), said liquid guide (3) comprising a valve body (10) for closing the liquid flow path (7), a pressure bearing sleeve (11) formed integrally with the valve body (10), an anchor member (12) to be secured to the discharge pipe (F), and a spring member (13) for coupling said integrally formed valve body (10) and the pressure bearing sleeve (11) with the anchoring member (12),
said pressure bearing sleeve (11) has a pressure bearing surface (14) facing the upstream side of the liquid flow path (7) for bearing the liquid pressure,
an area of said pressure bearing surface (14) is so selected that a force generated by a proper liquid discharge pressure that is applied to said pressure bearing surface (14) is greater than sum of a resilient force of the spring member (13) and a force applied to the valve body (10) and directed to the downstream side of the liquid flow path (7),
an inner peripheral wall (31) of the cylinder (23) is provided with a plurality of short and shallow grooves (32) at a portion adjacent to a bottom wall (29) of the cylinder (23), said short and shallow grooves (32) running longitudinally,
the inner peripheral wall (31) of the cylinder (23) is provided with an air intake port (123) communicating with an inside of the container,
the piston (24) is formed with a pair of annular skirts (35, 37) held in close contact with the inner peripheral wall (31) of the cylinder (23), and
a gap separating said pair of annular skirts is so selected that, when one of the annular skirts (35) rides on the short and shallow grooves (32) of the cylinder, the other of the annular skirts (37) is brought into close contact with inner peripheral wall of the cylinder at a position close to an open edge of the cylinder than the air intake port (123).
The trigger type liquid discharge device according to the claim 2, wherein
a groove for the intake of air is formed on the inner surface of the cylinder between a first position where the annular skirt (35) rides on the short and shallow groove (32) and a second further position which is near the air intake port relative to a third position where the annular skirt (37) is positioned when the piston is positioned at the approach end.